Cron-Mbt

Cron-Mbt is a MoonBit cron expression library with a real parser, deterministic matcher, next-trigger calculator, and a usable CLI. The repository is being hardened for the MoonBit OSC2026 acceptance checklist, so the focus is on runnable examples, CI completeness, source clarity, and publish readiness rather than marketing-heavy claims.

What It Supports

Standard 5-field cron expressions: minute, hour, day-of-month, month, day-of-week.
Core operators: *, ?, ,, -, /, and L for the last day of month. L is accepted only in the day-of-month field; invalid placements return Err.
Macro aliases: @yearly, @annually, @monthly, @weekly, @daily, @midnight, @hourly.
Day matching semantics aligned with common cron behavior: when both day-of-month and day-of-week are constrained, either side may satisfy the schedule.
Sunday normalization for both 0 and 7.
A CLI that can parse expressions, check matches, and compute the next trigger time.

Why This Revision Matters

The organizer feedback highlighted several concrete gaps:

deprecated warnings blocked moon info / moon fmt style checks
CI did not cover the required check/build/fmt/info/test stages
the CLI was mostly a placeholder
the next-trigger logic was still minute-by-minute brute force and missed weekday constraints
Mooncakes metadata was incomplete

This revision addresses those issues directly.

Project Layout

src/cron/   core parser, matcher, scheduler, tests
src/cli/    command-line interface
docs/       architecture, API reference, acceptance notes, source notes
scripts/    validation and helper scripts
.github/    GitHub Actions workflow

Installation

Add the module to moon.mod:

[deps]
"cxh04/cron_mbt" = "0.2.1"

Library Usage

Parse and inspect an expression:

let expr = @cron.parse("*/5 8-10 ? * 1-5").unwrap()

Check whether a timestamp matches:

let matched = expr.matches(
  year = 2026,
  minute = 15,
  hour = 9,
  day_of_month = 10,
  month = 6,
  day_of_week = 3,
)

Compute the next trigger time:

let expr = @cron.parse("30 9 * * 1").unwrap()
let current = {
  year: 2026,
  month: 6,
  day: 9,
  hour: 10,
  minute: 0,
}
let next = expr.next_time(current).unwrap()
// 2026-06-15 09:30

CLI Usage

Parse:

moon run src/cli parse "0 9 ? * 1-5"

Next trigger:

moon run src/cli next "30 9 * * 1" 2026 6 9 10 0

Match a timestamp:

moon run src/cli match "15 10 * * *" 2026 6 10 10 15 3

Verification

Local checks used during this hardening pass:

moon check --deny-warn
moon build
moon fmt
moon info
moon test --deny-warn
moon run src/cli parse "0 9 ? * 1-5"
moon run src/cli next "30 9 * * 1" 2026 6 9 10 0
pwsh ./scripts/verify_acceptance.ps1

The CI workflow uses the official MoonBit installer, prints moon version --all, and runs moon check --deny-warn, moon build, moon fmt, moon info, and moon test --deny-warn.